The invention relates to a method of controlling an automated gear shift transmission that is installed in a motor vehicle, comprising several forward and at least one reverse gear and that allows choosing from several different driving modes by means of a driving mode selector lever.
From the DE 101 09 662 A1 a method of controlling the automated gear shift transmission designed as a dual clutch transmission is known, comprising a first partial gearbox having a first clutch and a first group of gears; and comprising a second partial gearbox having a second clutch and a second group of gears, wherein in a change-direction mode in that repeatedly a change of direction between the driving direction of the motor vehicle forward and reverse takes place, and wherein in one of the partial gearboxes a forward gear is kept permanently engaged and in the other partial gearbox comprising a reverse gear this reverse gear is kept permanently in engagement, and wherein a change of the driving directions is accomplished by alternatingly opening and closing the clutches in one of the gearboxes and closing or opening the clutches in the other partial gearbox, respectively. Such a change of direction of the motor vehicle is for instance helpful for routing into and out of parking spots and rocking the motor vehicle out of snow. Since due to the permanently engaged gears it is only necessary to activate the aforementioned clutches and not in addition the gear shift clutches allowing engaging and disengaging the particular gears, a change of the driving the direction can be accomplished quickly and with little wear. Therefore, this method of controlling the two dual clutch transmissions contributes to the driving comfort and to a long life cycle of the motor vehicle.
In the EP 1 681 497 A2 likewise a method of controlling a dual clutch transmission is described that enhances the driving comfort of the motor vehicle. According to this method, an undesired start-up creeping action of the motor vehicle in the case of lower temperatures should be eliminated.
The undesired start-up creeping action of the motor vehicle is attempted to be avoided in that in the dual clutch transmission in one of the partial gearboxes a forward gear and in the other gearbox a reverse gear are maintained in engagement while for the dual clutch transmission during the non-moving state the motor vehicle a non-driving mode (parking mode or idle driving mode) is chosen. By means of the engaged gears a creeping action of the motor vehicle is avoided since the drag torques occurring even with open clutches due to the high viscosity of the clutch fluid in case of low temperatures and these torques that at are transmitted by the clutches compensate each other to the extent that a creeping action is avoided.
For further or specific driving conditions of the motor vehicle, for instance in case of starting up at an uphill inclined road or downhill inclined road, a specific control of the dual clutch transmission is desirable. However, this requires a sensor or another previously performed method for determining these specific driving conditions. In case of a control during the start-up action of the motor vehicle at an uphill incline it would for instance be necessary to use an incline sensor or to analyze the vehicle acceleration while taking the driving resistance graph into consideration. A main problem for determining an uphill incline by means of a driving resistance graph is that the motor vehicle has to be in motion for this purpose. However, if the apparatus for controlling the dual clutch transmission is just starting up or the motor vehicle is not moving, no information can be acquired as to the inclination of the road, for instance for adjusting the start-up action on a hill. For this purpose, an inclination sensor has to be provided resulting, however, in additional costs.